Such cameras are used in computer tomography, ultrasonic diagnostics, nuclear-medicine image plotting for the purpose of documentation and recording. Several images from a screen are captured on a film sheet. The film sheet is then developed in a different station.
An apparatus of the kind mentioned at the beginning has become known from the publicly distributed copy of Dutch Application No. 8,102,729. This apparatus has the following disadvantages:
(a) The camera is relatively large in volume because the guide rods for guiding the film sheet carrier and for guiding the monitor, the mirrors and the lens system have to be long. At least 3 mirrors are necessary. This results in a loss of light, since, when new, a mirror has a maximum efficiency of 95% and later it has an efficiency of 90%. After some time, one therefore only obtains an efficiency of 73%. PA1 (b) Relatively large masses of sensitive parts have to be moved. Although the enlargement scale cannot be changed, the entire monitor/mirror/lens system has to be moved. Such unnecessary movements impair however the service life of the screen tube, even if rubber belts are inserted between the drive motors and the highly sensitive parts so as to cushion the starting jerk and the braking jerk. Apart from this, rubber belts produce an abrasion that is detrimental to the optical properties. PA1 (c) Two of the three necessary mirrors are always directed upwardly and are therefore particularly exposed to the risk of dust settling thereon. PA1 (d) To prevent the apparatus from being even larger in construction than it is in any case, it is imperative that the screen tube should be arranged horizontally in the apparatus. This is however an unfavourable position for a moved screen tube. PA1 (e) The construction makes it impossible to photograph the screen in different enlargements. PA1 (a) the screen is parallel to the image plane of the film sheet, PA1 (b) a base is provided which is parallel to the film sheet, PA1 (c) a swivel flange is provided coaxial with the central axis of the screen which can be swivelled about the base through at least 180 degrees and which is optically open towards the screen, PA1 (d) an extension housing is carried on the base, in which the 45 degree mirrors together with the lens system are accomodated and which can be swivelled with the base through at least 180 degrees and is optically open towards the film sheet, PA1 (e) the optical axis of the extension housing is parallel in the 0 degree position and in the 180 degree position, and PA1 (f) the length of the optical axis of the extension housing equals approximately half the length of the diagonal of the panels.